Here's what rhymes with sifth.
fifth Words that almost rhyme with sifth
ifs sieves scythes riffs skiffs sniffs whiffs gives lives myths cliffs smiths writhes forgives hieroglyphs blacksmiths goldsmiths monoliths silversmiths filth scythe myth sixth width pith smith writhed writhe plinth therewith herewith hyacinth forthwith labyrinth wherewith monolith silversmith